Test Method Research Articles

Extended-spectrum β-lactamase and carbapenemase producing Enterobacteriaceae among patients suspected with surgical site infection at Hospitals in Southern Ethiopia

BackgroundExtended-spectrum β-lactamase and carbapenemase-producing Enterobacteriaceae are an increasing problem for patients today. Data on clinical samples for ESBL and carbapenemase-producing Enterobacteriaceae for surgical site infection patients in developing countries are limited, including Ethiopia, mainly due to resource constraints. Hence, this study aimed to determine the prevalence of extended-spectrum beta-lactamase- and carbapenemase-producing Enterobacteriaceae among patients suspected to have surgical site infection at Hospital in Southern Ethiopia.Materials and methodsA hospital-based cross-sectional study was conducted on 422 suspected surgical site infections from June 1, 2022 to August 30, 2022 at Hospitals in Southern Ethiopia. Sociodemographic and clinical data were obtained by using a structured questionnaire. Clinical samples (pus, pus aspirates, and wound swabs) were collected aseptically and processed within 30 min by placing the swabs in sterile test tubes containing sterile normal saline (0.5 mL). Samples were cultured on blood and MacConkey agar plates. All positive cultures were characterized by colony morphology, Gram staining, and standard biochemical tests. Antimicrobial sensitivity tests were performed using Kirby Baur disk diffusion on Mueller–Hinton agar. ESBL production was confirmed using a double-disc synergy test (DDST) method. Carbapenemase production was assessed using the modified Hodge test. Logistic regression analysis was used to determine associated factors. A P-value < 0.05 were considered statistically significant.ResultBacteria belonging to the order Enterobacterales were cultured in 23.7% out of 422 patients with suspected surgical wound infection. Of all the isolates, Enterobacteriaceae (69 isolates) were the most frequent, with E. coli (29/69) followed by K. pneumoniae (14/69). Of 69 Enterobacteriaceae isolates, 66.6 % (46/69) were positive for ESBL production, and 21.7 (15/69) were positive for carbapenemase-producing Enterobacteriaceae. The majority of Enterobacteriaceae isolates showed sensitivity to meropenem (72.1%); however revealed 63.9% and 70.5% were resistant to gentamicin and ciprofloxacin, respectively. Similarly, a higher resistance rate to cefepime (91.8%), amoxicillin-clavulanic acid (98.4%), ceftriaxone (95.1%), and ceftazidime (91.8%). MDR rate of Enterobacteriaceae isolates was 25/61 (41%) among patients suspected for surgical site infection. The Multivariable analysis revealed that length of hospital stay in hospital [AOR = 3.81 (95% CI 2.08–6.95)] remained statistically significant factor associated with surgical site infection due to ESBL producing Enterobacteriaceae.ConclusionStudy results showed the severity of ESBL-producing Enterobacteriaceae is critical and CPE is alarming. Meropenem is the most effective antibiotic against the ESBL-producing Enterobacteriaceae. MDR rate of Enterobacteriaceae isolates was 61 (61%) among patients suspected for surgical site infection. Therefore, antibiotic selection should be based on the results of the culture and sensitivity tests.

Microbiological Characteristics of Beef Sausage Enriched With Roselle (Hibiscus sabdariffa L.) Sepal Extract

ABSTRACTAdding plant extracts to sausage and other meat products is very important to improve their quality, safety, and durability. The aim of this study was to evaluate the microbiological properties of beef sausage enriched with roselle (Hibiscus sabdariffa L.) sepal extract. The total content of phenolic and flavonoid compounds in hydroalcoholic extract of Roselle sepals was measured by Folin‐Ciocalteu test and aluminum chloride colorimetric method, and antioxidant activity was measured by DPPH method. Pectin was used to encapsulate the extract. The characteristics of capsules, including particle size, zeta potential, and capsule efficiency were measured. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of extracts were performed by tube dilution method. Microbial tests were performed on sausage treatment samples. Analysis of the obtained data was done using SPSS and Excel software. The study revealed that the total phenolic and flavonoid compounds in the extract were 174.6 mg of gallic acid per gram and 16.8368 mg of quercetin, respectively. The extract displayed the highest antioxidant activity at elevated concentrations. Particle size ranged from 16.833 to 640.534 μm. The zeta potential and capsule efficiency were found to be satisfactory. Compared to the encapsulated extract, the free roselle extract better inhibited Staphylococcus aureus (s. aureus), Salmonella typhimurium (S. typhimurium), and Escherichia coli (E.coli). During storage until day 20, these bacteria did not grow in the free or encapsulated extract groups. However, S. aureus appeared in the free extract group from day 25 and the encapsulated extract group from day 20. Roselle extract has antimicrobial properties that can improve the quality and safety of beef sausage during storage.

Mobility forecast of gravel-silty clay landslide using ring shear test and discrete element method in Shaziba, southwestern Hubei Province, China

Mobility forecast of gravel-silty clay landslide using ring shear test and discrete element method in Shaziba, southwestern Hubei Province, China

Development of a method for the impact performance characterization of commonly worn helmets in rodeo bull-riding

As the rodeo sport of bull-riding increases in popularity, dangers to bull-rider athlete safety continue to pose serious health risks. Despite frequent occurrences of head trauma in the sport, current test methods for evaluating helmets commonly worn in bull-riding fail to consider rotational head acceleration, which is correlated to concussive events in impact sports. Additionally, the second most prevalent mechanism contributing to head trauma in bull-riding is bull kick impacts, which have yet to be accurately modeled in a test method. Researchers aim to enhance bull-rider athlete protection through the development of a helmet test method that simulates bull kicks with a pneumatic linear impactor. The proposed test method considers impacts at two impact velocities and six impact locations using a flat and Equestrian Hazard Anvil. Two commonly worn helmets in bull-riding are evaluated in this study, and an adequate sample size is determined from analyzing variation between repeated impacts. The proposed test method is statistically validated, and researchers show that impacts at higher kicking velocities and impacts with the flat anvil result in increased rotational head accelerations. Ultimately, this study emphasizes the need for helmets designed specifically for the unique impacts of bull-riding by simulating bull kicks through pneumatic linear impactor testing to reduce rotational head kinematics and hoof penetration.

Colistin, Meropenem–Vaborbactam, Imipenem–Relebactam, and Eravacycline Testing in Carbapenem-Resistant Gram-Negative Rods: A Comparative Evaluation of Broth Microdilution, Gradient Test, and VITEK 2

Objectives. This study aimed to evaluate and compare the performance of different assays for antimicrobial susceptibility testing (AST) and minimum inhibitory concentration (MIC) determination for reserve antibiotics in carbapenem-resistant Enterobacterales (CREs), Pseudomonas aeruginosa (CRPAs), and Acinetobacter baumannii (CRABs). Methods. An analysis was conducted on 100 consecutive isolates: 50 CREs, 35 CRPAs, and 15 CRABs. Sensititre broth microdilution was used as a reference standard to evaluate the performance of VITEK 2 card AST-XN24 (bioMérieux), the respective gradient tests (bioMérieux), and UMIC colistin broth microdilution test strips (Bruker Daltonics). Errors, essential agreement (EA), and categorical agreement of MICs for colistin (COL), meropenem–vaborbactam (MVB), imipenem–relebactam (IRL), and eravacycline (ERV) were assessed. Results. The agreement between both of the COL broth microdilution (BMD) methods was perfect (100/100). The gradient test and VITEK 2 analysis yielded comparable EA rates (92/100 and 72/79, respectively), with the latter not registering any very major errors (VMEs). The MVB gradient test achieved EA in 66 of 85 isolates and VITEK 2 in 70/85. For IRL, EA was reached in 69 and 64 of 85 cases by gradient test and VITEK 2 analysis, respectively. The ERV gradient test yielded false results in nearly all (12/15) CRABs but achieved EA in 46 of 50 CREs. The VITEK system recorded EA for ERV in 60 of 65 isolates. Conclusions. We observed substantial variability in the measured MICs between BMD and the alternative methods. In only a few constellations, VITEK 2 or gradient tests could substitute the reference method. BMD is the method of choice for COL analysis, with VITEK 2 representing an alternative method for CRPA testing. Alternative methods for MVB did not provide reliable results, except for Enterobacterales, when tested with the gradient test. However, resistant results need to be confirmed by BMD. Only BMD can be used for IRL MIC determination. VITEK 2 was mostly accurate in measuring ERV MICs, while the corresponding gradient test yielded reliable results exclusively in CREs. It is essential that laboratories are aware of which testing method provides reliable results for each combination of microorganisms and reserve antibiotics.

Electrical Resistivity Testing of Concrete Cylinders: Bias, Precision, and Use in Process Control

Electrical resistivity is increasingly used as a test method to assess the transport properties of concrete. This paper describes an interlaboratory study that was conducted to determine precision and bias for resistivity measurements made in surface and bulk configurations of concrete cylinders. Tests were performed following AASHTO T 358-22 and AASHTO T 402-23. A verification device is introduced with a known resistivity (and impedance) to aid in determining the bias associated with resistivity measurements. However, this device can also be used as a training tool and as a tool to evaluate the qualifications of those new to performing the test. Concrete cylinders were prepared, cured, and conditioned using three methods: immersed in simulated pore solution, sealed, and immersed in lime solution. The samples were tested to determine the precision in the resistivity measurements of the samples for the different curing conditions. The paper discusses how resistivity testing can be used for quality control testing as well as quality acceptance. The results were used to develop precision and bias statements for resistivity measurements, which have been adopted in the latest American Association of State Highway and Transportation Officials (AASTHO) standards.

Effect of nanoemulsion loaded with macela (Achyrocline satureioides) on the ultrastructure of Staphylococcus aureus and the modulating activity of antibiotics

Nanoformulations with herbal actives for treating bovine mastitis present an alternative for controlling bacterial infections in the emerging scenario of antimicrobial resistance. In this study, we investigated macela (Achyrocline satureioides) nanoemulsion (NE-ML), a formulation developed for the treatment of bovine mastitis (registered under Brazilian patent application BR 10 2021 008630 0), in the context of its bactericidal mechanism(s) of action and potential synergism with commercial antimicrobials. The effect of NE-ML on the integrity and cell permeability of Staphylococcus aureus was evaluated by measuring the electrical conductivity of bacterial suspensions exposed to different concentrations of NE-ML and by assessing the release of cellular constituents. Damage to bacterial ultrastructures was analyzed by transmission electron micrographs. The synergism of NE-ML with beta-lactam antibiotics and aminoglycosides was evaluated by the checkerboard test method against S. aureus (n = 6). The relative electrical conductivity of the bacterial solution gradually increased over time, reaching high values after exposure to 1xMIC (52.3%) and 2xMIC (75.34%) of NE-ML. Total proteins were detected in the bacterial suspensions exposed to NE-ML, increasing in concentration over exposure time (p < 0.05). Through bacterial micrographs, we observed that exposure to NE-ML (1xMIC) affected the integrity of the plasma membrane with invaginations in the cytosolic region and alterations in the cell wall. The increase in NE-ML concentration resulted in greater damage to the ultrastructure of S. aureus with changes in bacterial cell division patterns. When NE-ML was combined with the beta-lactam antimicrobials, the interaction was indifferent, indicating no modulation of antimicrobial resistance. In contrast, when combined with the aminoglycoside, a synergistic interaction did occur. These general findings suggest that the bactericidal action of NE-ML begins in the plasma membrane, causing alterations in its permeability and integrity, and extends to the cell wall, cytoplasm, and cell division. Although synergy was restricted to the aminoglycoside by destabilizing the bacterial cell membrane, this suggests that NE-ML can induce the entry of other actives, potentially reducing their therapeutic doses. Understanding the mechanism of action of this new nanoformulation is certain to drive pharmacological advances, broaden the perspective of its in vivo use, and improve the treatment of bovine mastitis.

Comparative Analysis of Quasi-Linear Kalman-Type Algorithms in Estimating a Markov Sequence with Nonlinearities in the System and Measurement Equations

The so-called Kalman type algorithms (KTA) are considered, among them quasi-linear KTAs introduced as a separate class, the features of which are the Gaussian approximation of the a posteriori probability density function (p.d.f.) at each step and the procedure for processing the current measurement based on the ideology of a linear optimal algorithm. The unified structure of such algorithms and their features are discussed. Two groups are distinguished the quasi-linear KTA: the first is algorithms using Taylor series expansion of the nonlinear functions, and the second is the so-called linear regression KTA. The methods of their designing are considered, and the common features are described. Detailed attention is paid to the following KTAs: the extended Kalman filter (EKF), polynomial filters of the second and third order (PF2 and PF3), as representatives of the first group, and the Unscented and Cubature Kalman filters (UKF and CKF), as representatives the second one. Their comparative analysis is carried out using the estimation problem of a scalar Markov sequence in the presence of nonlinearities in the shaping filter and in the measurement equations. For all the studied algorithms, the formulas are given in a form convenient for comparison. Based on these formulas, possible causes of a decrease in accuracy and a violation of the consistency properties are identified. Using the previously proposed procedure based on the method of statistical tests, predictive simulation was carried out, which made it possible to confirm the conclusions obtained previously on the basis of an analysis of the formulas for the algorithms being compared. The simulation also allowed to compare the computational complexity of the compared algorithms. The results of the study may be useful to developers involved in the processing of measurement information when choosing a filtering algorithm for solving specific practical estimation problems.

Research on the determination and influencing factors of topographic unsymmetrical-loaded tunnels based on the unsymmetrical coefficient

The accurate judgment of topographic bias tunnels is directly related to reasonable tunnel design and construction safety. In this study, numerical simulations were carried out to determine the unsymmetrical coefficient of topographic unsymmetrical-loaded tunnels, according to the critical thickness of the cover layer of the topographic bias tunnel proposed in the Chinese Code. The unsymmetrical coefficient was analyzed via control variable method and orthogonal test method. The results showed that it is appropriate to take 1.2 as the criterion for all types of topographic unsymmetrical-loaded tunnel in practical application. The influence of different topographic factors, mechanical properties of the surrounding rock, rock quality, construction methods and tunnel spans on the unsymmetrical coefficient were summarized by the control variable method. The results of multifactor analysis under an orthogonal design revealed that the influence of Uc is in the following order: slope angle, overburden thickness, construction method, surrounding rock quality, and height-to-span ratio.Article HighlightsThe Chinese code for topographic unsymmetrical-loaded tunnels presents a the determination of the corrected unsymmetry coefficient.Single-factor analysis determines the change pattern of the corrected unsymmetry coefficient under the influencing factors.Polar analysis based on orthogonal tests determines the strength of the factors influencing the corrected unsymmetry coefficient.

Application of Artificial Intelligence Technology for Prompt Diagnosis of Cast Iron Mechanical Properties

Kinetic indentation is widely used to measure physical and mechanical properties of materials as one of the most universal methods for non-destructive testing. This paper uses the latest advances in artificial intelligence and capabilities of the Python programming language libraries allowing to carry out accurate measurements of cast iron hardness based on the data of the material’s micro-impact loading diagram. It has been shown that use of machine learning allows eliminating gross errors and reducing the error of indirect hardness evaluation in several times – down to 10 units according to Brinell HB. It has also been established that formation of additional features for training models (based on traditionally used characteristics: penetration depths, indenter movement speed and contact forces at certain points in time) has a positive effect on the accuracy of measurements, but amount of measurements should also be optimized. Feasibility of effective use of machine learning to evaluate hardness has been demonstrated by comparing of calculated hardness values with data obtained with standard testing methods. Advantage of the developed testing method is the fact that the developed algorithms can be used for prompt diagnostics of cast iron hardness using existing equipment. It is appropriate to extend the proposed approach for determination of other mechanical properties of cast iron: yield strength, strain hardening index, creep, relaxation, determined by indentation methods.

Wear properties of Al6061/SiC + B4C + TiC hybrid composites produced by vacuum infiltration method

Abstract In the study, hybrid metal matrix composite (HMMC) structures were produced by vacuum infiltration method (VIM) using Al6061 alloy and varying amounts of SiC, B4C, and TiC ceramic powder pairs. Age-hardening processes were applied to these HMMCs. After heat treatment, wear behavior was examined under different loads using the pin-on-disc test method. All Al6061 hybrid composites exhibited better wear performance than unreinforced Al6061. In the wear tests of composite samples, the lowest volume loss and therefore the highest wear resistance were obtained in Al6061 3 wt.% B4C + SiC composites under 5 N force. The lowest wear resistance due to the highest volume loss was determined in Al6061/1 wt.% TiC + B4C composites under 15 N force. Abrasive and adhesive wear characteristics were observed in field emission scanning electron microscopy(FESEM) images of worn surfaces. Additionally, wear debris, smearing, and deep grove formations were determined on the surface. In the EDS analysis performed on the worn surface, O and Fe elements were found in addition to the elements that are likely to be in the structure (such as Al, B, C, Ti, Si, and Mg). The wear tests caused the formation of oxide layers on the sample surfaces.

A Statistical Analysis of Factors Affecting VOT and F0 in Plosive Sounds across Chinese, Japanese, and Korean

Purpose: To conduct a statistical analysis of the acoustic features of VOT and F0 in plosive sounds across Chinese, Japanese, and Korean. The goal is to determine the impact of three factors—manner of articulation, place of articulation, and tone type—on VOT and F0, providing theoretical support for future "simultaneous cross-linguistic comparison studies" of plosive sounds in these three languages. Approach/Methodology/Design: A total of 792 word-initial plosives were selected from news broadcasts of official media in Chinese, Japanese, and Korean. Three variables—manner of articulation, place of articulation, and tone type—were set, and the S-N-K test and Bonferroni multiple comparison method were used to evaluate whether these variables had significant effects on the word-initial plosives. Findings: For VOT, the manner of articulation has the most significant effect across Chinese, Japanese, and Korean. The place of articulation has a lesser impact, while tone type has no effect on VOT, except in Korean, where there is no tone distinction for word-initial plosives. For F0, tone type significantly influences F0 in Chinese, while manner and place of articulation have minimal impact. In Japanese, both manner of articulation and tone type significantly affect F0, but place of articulation does not. In Korean, only the manner of articulation significantly affects F0. Originality/Value: Previous studies on word-initial plosives in Chinese, Japanese, and Korean have primarily focused on VOT, with limited research on F0, especially for Chinese and Japanese, where studies on F0 are scarce. This study is the first to analyze different tone types of Chinese and Japanese as variables in the acoustic analysis of plosive sounds. Past studies typically involved general native speakers, with little emphasis on the standard pronunciations of professional broadcasters. With the introduction of Chinese-Korean bilingual broadcasting majors in 2021 and Chinese-Japanese bilingual broadcasting majors in 2024 in China, this research also provides theoretical support for the education and training of multilingual broadcasting professionals in Chinese, Japanese, and Korean.

Simulation and Experimental Study on Indentation Rolling Resistance of a Belt Conveyor

In this paper, in order to reduce the indentation rolling resistance of a belt conveyor and improve its operation efficiency, the indentation rolling resistance of a belt conveyor is studied. Firstly, the theoretical calculation of the indentation rolling resistance caused by the contact between a conveyor belt and an idler is studied. Additionally, the expression of the indentation rolling resistance including the multi-element Maxwell relaxation modulus is simplified and deduced using the assumption of small deformation, and the steps of iterative calculation of the indentation rolling resistance through setting the initial values are designed. Then, the multi-component Maxwell relaxation modulus function of the conveyor belt tested in the previous work of the authors is substituted into COMSOL 5.6 finite element software, and the stress distribution caused by the contact between the conveyor belt and the idler under different working conditions is analyzed. Also, a series of measures to reduce the indentation rolling resistance are found through the laws presented by the simulation results. Finally, the experimental study of the indentation rolling resistance is carried out using the indentation rolling resistance testing device from our research group. By comparing the experimental results for the indentation rolling resistance under different working conditions with the theoretical calculation results for the indentation rolling resistance, it was found that the relative error was less than 13%, which proved the feasibility of the indentation rolling resistance and relaxation modulus testing method, as well as the theoretical calculation method for indentation rolling resistance.

KAMPO SI-SHEN EXTRACT PREVENTS LPS-INDUCED WORKING MEMORY IMPAIRMENT AND DEPRESSIVE BEHAVIOR IN MICE

Si-Shen decoction is a mild medicinal dietary material composed of lotus seeds, gorgon, poria and yam. In vitro studies have proved the biological activity of four individual medicinal materials, but the effects of the combination prescription have yet to be evaluated in vivo in the past. This study prepared the Si-Shen extracts (SSE) by heating reflux with 50% alcohol. The prepared extracts contained functional components, including [Formula: see text][Formula: see text]mg of QE/g of flavonoids and [Formula: see text][Formula: see text]mg of GAE/g of polyphenols. The antioxidant activity of SSE was verified by the DPPH and FRAP assays. Moreover, the prepared SSE is not cytotoxic below the concentration of 2[Formula: see text]mg/mL according to the ISO10993-5 test method. Feeding the SSE for 28 days is sufficient to prevent lipopolysaccharide (LPS)-induced spatial memory impairment and anxiety symptoms, and SSE improves physical fitness. Further experiments demonstrated that SSE elevated the level of acetylcholine in the brain and serum superoxide dismutase activity. This research demonstrated the apparent efficacy and safety of the SSE, which will be further developed into innovative health products related to disease prevention.

An accelerated corrosion-fatigue testing method for marine high-strength steel based on equivalence principle of fatigue crack growth

The corrosion-fatigue test is widely used to assess marine equipment. However, due to the low-frequency and high-cycle loading of marine equipment in service, conventional test methods require long cycle times and high costs. This makes it challenging to meet the rapid evaluation demands associated with equipment development effectively. In this study, an accelerated corrosion test method was proposed for steel by adjusting the composition, temperature, pH and H2O2 concentration of environment. Fatigue crack growth tests were conducted under various corrosion environments and load frequencies. The matching relationships between corrosion fatigue acceleration multiplier, corrosion environment parameters and load parameters were established. Additionally, a corrosion fatigue acceleration test method was proposed based on the equivalent principle of fatigue crack growth. The results show that effective coupling between corrosion and fatigue can be achieved by gradually reducing the load frequency as the stress intensity factor amplitude increases throughout the crack growth process. It is consistent with the trend of fatigue crack growth rate in the seawater environment. The 4.85% fatigue life deviation and the 15.68 times corrosion fatigue acceleration can be achieved by our method. This work improves the accuracy and reliability of fatigue performance evaluation for offshore equipment.

Fosfomycin—Overcoming Problematic In Vitro Susceptibility Testing and Tricky Result Interpretation: Comparison of Three Fosfomycin Susceptibility Testing Methods

Background: Fosfomycin (FOS) is an older antimicrobial agent newly rediscovered as a possible treatment for infections with limited therapeutic options (e.g., Gram-negative bacteria with difficult-to-treat resistance, DTR), especially in intravenous form. However, for correct usage of FOS, it is necessary to have a reliable susceptibility testing method suitable for routine practice and robust interpretation criteria. Results: The results were interpreted according to 2023 interpretation criteria provided by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). DTR Gram-negatives were more likely to be resistant to FOS (45% in Enterobacterales and 20% in P. aeruginosa) than non-DTR (10% and 6.7%, resp.). All isolates of S. aureus were susceptible to FOS. In Gram-negatives, all agreement values were unacceptable. Etest® performed better in the DTR cohort (categorical agreement, CA, 80%) than in the non-DTR cohort (CA 45.7%). There were no very major errors (VREs) observed in P. aeruginosa. S. aureus had surprisingly low essential agreement (EA) rates (53% for MRSA and 47% for MSSA) for Etest®, but categorical agreement was 100%. Methods: A total of 130 bacterial isolates were tested and compared using the disc diffusion method (DD) and gradient strip method (Etest®) with the reference method (agar dilution, AD). The spectrum of isolates tested was as follows: 40 Enterobacterales (20 DTR vs. 20 non-DTR), 30 Pseudomonas aeruginosa (15 DTR vs. 15 non-DTR), and 60 Staphylococcus aureus (30 methicillin-susceptible, MSSA, vs. 30 methicillin-resistant, MRSA). Conclusions: Neither one of the tested methods was identified as a suitable alternative to AD. It would be beneficial to define more interpretation criteria, at least in some instances.

A Comparative Study of the Rate of Helicobacter pylori infection Using Three Diagnostic Techniques among Patients in Rivers State

Background: Approximately 89% of gastric cancers are attributable to H. pylori infection, however, only 1 in 5 patients survive longer than 5 years after diagnosis. Evidence has shown that screening and eradication of H. pylori in young adults would be cost-effective and could prevent 1 gastric cancer in every 4 to 6 cases. Diagnostic tests used to detect Helicobacter pylori are either invasive or noninvasive methods. These tests have varying sensitivity and specificity, having about 90% accuracy in the diagnosis of H. pylori infection in clinical practice. Aim: This study aims at detecting Helicobacter pylori using antibody-antigen, stool antigen and polymerase chain reaction (PCR) and to compare the infection rate among the different diagnostic techniques. Methodology: This was a cross-sectional study. The participants included attendants to tertiary and private hospitals in Port Harcourt metropolis for medical treatment. Blood and stool samples were collected from one hundred and eighty (180) subjects aged 1 to 60 years and above. Ethical approval for the study was obtained from the Rivers State University Teaching Hospital Ethics Committee. Convenience sampling technique was deployed. Samples were collected from subjects who consented to the study. All samples collected were analyzed in Medical Microbiology Laboratory, Rivers State Teaching Hospital and subsequently, molecular analysis was carried out. Results: The blood antibodies test (serology) method shows a greater number of positive cases (43.9%) than stool antigen method (8.3%). Also, out of the 75% stool antigen positive samples, subjected to more specific PCR, only 25% were positive. There was a significant difference (p-value of <0.001) in sensitivity between antigen and serology, there was also a significant difference (p-value of <0.025) between antigen and PCR result outcomes. Conclusion: The study has shown that there is a notable variation in the diagnosis of H pylori among the laboratory techniques used.

Development and Application of a TaqMan RT-qPCR for the Detection of Foot-and-Mouth Disease Virus in Pigs

The global livestock industry is facing a serious threat from a widespread foot-and-mouth disease virus (FMDV) epidemic. The timely detection of FMDV can significantly mitigate its harmful effects. This study aimed to establish and evaluate a TaqMan fluorescence quantitative PCR assay to assess its sensitivity, specificity, reproducibility, and stability. The standard curve equation range is 6.43 × 109–6.43 × 101 copies/µL, with an R2 value of 0.996 and a standard curve equation of y = −3.586x + 36.245. The method successfully detected 64.3 copies/µL of the target gene for FMDV and exhibited high specificity for FMDV. Repeatability tests demonstrated low coefficients of variation within and between groups (<2%), indicating good reproducibility. The clinical samples analyzed using this method showed results consistent with those of the SYBR Green I RT-qPCR assay, confirming the reliability of the method. Overall, the developed test method displayed high sensitivity, specificity, reproducibility, and stability, making it suitable for the rapid diagnosis of foot-and-mouth disease in clinical settings.

Computational and experimental studies of vibration-protective properties of a pneumatic wheel of the MTZ-82 BELARUS tractor with external spring-hydraulic mini-suspension

BACKGROUND: Currently used in various sectors of the national economy, numerous wheeled suspensionless vehicles on pneumatic tires have a low level of vibration protection of the frame and limited cross-country ability. Therefore, the development and study of the design characteristics of a pneumatic wheel with increased elastic-damping properties and cross-country ability is a relevant technical problem. AIM: Development of the design and study the vibration-protective properties of a pneumatic wheel with an external spring-hydraulic mini-suspension to improve the ride smoothness and cross-country ability of large-sized suspensionless vehicles. METHODS: A description of the design of a wheel with mini-suspension and a support roller is presented. The wheel modeling was carried out in the PascalABC software, which takes into account the nonlinearity of the total force of the pneumatic tire and the spring-hydraulic mini-suspension, which is installed parallel to the tire at an angle to the vertical axis of the wheel. The test method consisted of comparison of free and forced vibrations of the rear pneumatic wheel of the MTZ-82 BELARUS tractor with a 400-965/15.5-38 tire, which operated without and with mini-suspension at a vertical load of 0.6 tons and various excessive pressure in the tire. RESULTS: The results of computational and experimental studies show that if the tire is radially compressed by 75 mm, the excess pressure inside the pneumatic wheel almost does not change, and if the pressure in the tire decreases from 1.6 to 0.4 bar, the resonant vibration frequency of the standard wheel axle decreases by 25%, while the dynamic coefficient remains unacceptably high (more than 5), leading to the tire breakaway from the supporting surface. Installing a mini-suspension parallel to the wheel in the form of a spring-hydraulic shock-absorbing strut leads to an increase in the resonant frequency by 1 Hz, however, the resonant peaks are reduced by almost 3 times to a dynamic coefficient of 2.5...2, which significantly increases the ride smoothness of suspensionless vehicles and reduces the likelihood of wheel breakaway from the supporting surface. CONCLUSION: It was found with the studies that the proposed wheel with a mini-suspension as a spring-hydraulic strut and a support roller has a relatively simple design, ensures high vibration-protective properties with small amplitudes of kinematic disturbance and can be used to improve the ride smoothness and cross-country ability of wheeled suspensionless vehicles.

Comparison of three different ice hockey helmets using an ice hockey specific test protocol

Although there are currently no standard tests measuring rotational head motion for ice hockey, researchers have proposed test methods which induce rotational head motion from an impact and may reflect more closely how concussions occur in the sport. Recently, Meehan et al. developed a test method for ice hockey helmets to represent concussive injuries associated with ice hockey. While that provided a method that used impact parameters closer to what may be experienced, the research did not evaluate if different helmets would produce differing results under those loading conditions. The purpose of this study is to use the methods developed by Meehan et al. to evaluate the protective capacity of three different ice hockey helmet designs. This research used monorail drop rig and pneumatic ram systems to follow the protocol of Meehan with a bare headform condition and three different helmet designs, allowing for differences in linear and rotational acceleration, rotational velocity, and maximum principal strain to be determined. The results of this research found that the test method developed by Meehan et al. does result in significant differences between different helmets and helmet designs under identical impact conditions. However, these differences were limited which may be a reflection of the test method as well as commonality in terms of how ice hockey helmets are designed; the different models may not be sufficiently different enough to provide different results under these loading conditions.